Method of printing and apparatus therefor



Jan. 7,' 1941. AF R 2,227,882

METHOD OF PRINTING AND APPARATUS THEREFOR Filed March 5, 1957 3Sheets-Sheet fi ZL'O Jffrz/an- 5 MM, 5 012 M242 1,

Jan. 7, 1941. P. FRAZIER METHOD OF PRINTING AND APPARATUS THEREFOR 3Sheets-Shet 2 Filed March 5, 1937 P. A, FRAZIIER Jan. 7, 1941 I METHODOF PRINTING AND APPARATUS THEREFOR Filed March 5. 19s? 3 Sheets-Sheet 3Patented Jan. 7, 1941 UNITED STATES METHOD OF PRINTING AND APPARATUSTHEREFOR Philip A. Frazier, Oak Park, Ill.- ApplicationMarch 5, 1937,SerialNo; 129,211

5 Claims.

This invention relates in general to the art of letterpress, direct orrelief printing, and more particularly to improvements in the method andapparatus of providing resiliency in printing, to the end that theirregularities under the printing surface are compensated for during theprinting operation. The invention further relates to method andapparatus for obtaining a so-called squeeze impression.

It is well known to those skilled in the art that the finest commercialprinting is accomplished when two relatively hard printing surfaces areemployed. This method requires such precision and skill that forordinary purposes its use is practically prohibitive. In. ordinarypractice it is necessary to build up both printing. surfaces by means ofvarious paoltings'v in the. form of underlays and overlays. The presentinvention contemplates obtaining a squeeze impression by methods andapparatus unknown to the art. The invention relates to letterpressprintin employing wood mounts or metal bases in fiat bed or platenpresses or curved-plates carried on cylinders in rotary presses and maybe employed with any type of printing plate, for example, electrotypes,streotypes, zinc, or copper plates.

tary presses.

By direct relief or letterpress printing is meant that class of printingwhich is carried out on standard presses in which the surface supportingthe material to be printed upon, which is of a relatively soft orembossable nature, is maintained during printing at a fixed distancefrom the surface supporting the plate by which the printing is done. Theplates are of the type known as letterpress in which the printingsurfaces are raised above thegeneral level of' the plate. Inletterpress: printing; the printing pressures are developed bycompression of the, material to be printed upon, held between rigidsurfaces which are maintained apart at predetermined. distances.

In letterpress printing, more or less pressure is required tosatisfactorily transfer ink from the printing surface to thematerial tobe printed. All the mechanical inaccuracies in the printing surface, thesupport for the printing surface and the support for the material to beprinted become apparent in the printed impression becauseof theapplication of pressure. Letterpressmen have attempted for years tocompensate for these minuteinaccuracies. Obviously, a non-yieldingsupport for the printed material would gave a sharp definition to theprinted subject, but a non-yielding support cannot be used because ofthe mechanical difficulties involved in presenting an absolutelyaccurate printing surface and support for the printing surface,

The invention finds a widefield of utility for the purposesindicat'edLin flat bed and ro- In order: to absorb the. variations inpressure arising from inaccuracies in the printing, surface and printingsupport, a relatively soft or yielding support for the printed materialwas employed; The employment of a relatively soft oryieldingsupportingmember for the material to, be printed. permittedthehigh characters in the printing element to push into the supportingmember, which resulted in embossing the printed material, known asimpression. It was, therefore, necessary to alter the surface. of thesupporting member to compensate for inequalities of pressure by cuttingaway where impression showedi and building up the supporting surfacewhere more pressure was needed. Altering the surface of the support forthe material to be printed is called make-ready. The term make-ready hasalso been used to denote various other steps such as leveling up theform, but for the present purposes limited sense. Make-ready isexceedingly costly, in that it is laborious, requires several proofprintings and necessitates the services of skilled and experiencedprinters. The costs of printing are greatly increased by the fact thatthe presses are idle during make-ready.

In a platen press, make-ready does no harm other than toadd to ind'erpress the distorted circumference of the impression cylinder, due tomake-ready, tends to become in untimed relation to the speed of theprinting element supported on the reciprocating bed, resulting inproducing sheets out of register, stretched sheets, slurs and wornplates. In rotary presses, particularly web presses, the samedifficulties are presented, but in the case of stretched sheets andregister the difficulties are cumulative and may also result in breakingthe Web.

It is, therefore, an object of the present invention to eliminate thenecessity for makeready as well as the time consuming make-ready itself,and the above mentioned difficulties arising from the use of make-ready.Only a small proportion of the mechanical inaccuracies in printing arisefrom inaccuracies in the printing surface, and it has been found thatthese inaccuracies may be compensated for by employing a slightlyyielding support for the material to be printed. B yieldingly supportingthe printing element, all other mechanical inaccuracies may be absorbed,and a printing structure is obtained adapted to produce a perfectprinting impression if the surface of the printing element is relativelyuniform, for example, as in a page of type matter. However, to obtain aneven impression from a printing element having a halftone and blankportions on its printing surface, additional or less pressure,respectively, is required. If the same pressure is applied to the theterm is used in its I the cost. In a fiat bed cyl-.

type on the printing surface as is applied to the half tones thereon,there is serious danger of punching through or securing too heavy or anuneven impression. Accordingly, means is provided beneath the printingsurface to supply pressure appropriate to the various portions of theprinting surface.

A further object of the invention is to secure a finer grade printingthan has been formerly possible in ordinary commercial printing. Inaddition thereto a further object of the-present invention is to providea method and apparatus to obtain a squeeze impression by employing arelatively harder impression surface than printing surface and at thesame time to secure sufficient printing pressure to form a clear,distinct impression without punching through or slurring.

A further important object of the invention is to provide methods andmeans of yieldingly supporting a printing element, such as a plate, inprinting position, the plate being yieldingly supported throughout itsentire area, whereby printing pressure between the plate and the surfacebeing printed may be substantially uniform throughout the area of theplate, to the end that the resulting printing is of uniform texture.

A further object of the invention is to provide a printing structurewhereby the printing mount or plate may be employed in subsequentprinting operations without the necessity of providing new or additionalmake-ready.

A further object of the invention is to provide a method and apparatusfor regulating the varying amounts of pressure required to printdifferent portions of a printing plate embodying half tones and ordinarytype without overlay.

A further object of the invention is to provide a method and apparatusfor printing, in which a uniform printing impression may be obtained inreciprocating presses in which the bearer rails have become worn,thereby changing the adjustment between the impression cylinder and thetravel of the bed. In accordance with the present invention provision ismade for compensating any wear on the bearer rails, and the adjustmentbetween the cylinder and bed is not altered when the rails become worn.

A feature of the invention is the provision of mean-s of absorbingpressure variation arising from irregularities in the printing andimpression surfaces, plates, beds and cylinders without resort tomake-ready. An additional feature of the invention is the provision ofmeans of regulating the varying amounts of pressure required to printdifferent portions of a printing plate or plates by means of a patternedresilient material wherein the pattern of the underlay is changed toconform with the requirements of the printing surface.

It has been found that the foregoing desirable results may be obtainedby employing resilient material between the curved printing plate andprinting cylinder in rotary presses and between the printing plate andbase in flat bed presses, by means of which the printed impression is ofuniform texture, due to the fact that its resilient material will absorbinaccuracies in the bed and printing element. Any slight inaccuracies inthe printing surface may be absorbed by employing a slightly yieldingsupport for the material to be printed.

An additional feature resides in the provision of resilient materialwhich may be conveniently manufactured in sheet form in large quantitiesand stored with a view towards commercial practicability and convenienceto the electrotyper or printer.

An additional feature resides in the provision of a printing structureadapted to print evenly upon material of different thicknesses withoutadjusting the printing members. For example, paper cloth and cardboardof 'diiferent thicknesses may be printed upon by the improved structurewithout adjusting the printing members.

The printing surface may be yieldingly supported by interposingresilient material having a pattern temporarily displaceable between theplate and base. Satisfactory results have been obtained by employing astrip of rubber matting or any resilient composition having compressibleprojections, thereby increasing the displacement space when pressure isapplied. Where additional or less pressure is required as in the case ofhalftones and blank portions, respectively, additional or less pressuremay be provided by varying the thickness or resiliency of the yieldingmaterial or by varying the displacement space of the yielding materialor its supporting area.

The invention will be readily understood from the following descriptionin conjunction with the accompanying drawings in which preferredembodiments of the invention are shown.

In the drawings:

Fig. 1 is a perspective view of a printing block embodying theinvention;

Fig. 2, a side elevational view of a printing block embodying theinvention;

Fig. 3, a side view, partly in elevation and partly in section, takenalong lines 3-3 of Fig. 4 of a plate mounted upon a honeycomb baseembodying the invention;

Fig. 4, a plan view of bodying the invention;

' Fig. 5, a side elevation of the impression cyl inder and platecylinder of a rotary press embodying the invention;

Fig. 6, a side elevation of a plate cylinder, un'derlay, and curvedprinting plate, the parts being shown in disassembled relationship;

Fig. 7, a sectional view of a plug adapted to be inserted in a printingbase;

Fig. 8, an end view of an impression cylinder embodying a feature of theinvention;

Fig. 9, an enlarged plan View of one form of resilient matting uponwhich a printing plate may be mounted; and

Fig. 10, an enlarged, vertical sectional view of the resilient mattingshown in Fig. 9.

Referring to the embodiment shown in Figs. 1 and 2, the referencecharacter 8 indicates a printing mount of wood which, when assembled andlocked with other similar mounts, forms a printing foundation. A strip 9of resilient material lies between the upper surface 0 of the b k a anda printing plate I I. The resilient strip 9 preferably comprises arubber matting l2 having a fabric backing I3 and projecting disks M ofcompressible rubber.

Satisfactory results have been obtained by employing a resilientmaterial or matting of .046 inch thickness under acker gauge reading,but it is to be understood that the invention is not limited thereto andthat the resilient matting or material may be varied either way. Asshown in Fig. 10, which is enlarged approximately six times, theresilient projecting portions M are approximately .028 inch thick underHacker gauge reading. The

a honeycomb base emthickness of the resilient portions 14, as shown inFig. 9, are spaced apart from one another to afford a displacement area,and it is to be understood that the shape, height and spacing of theresilient portions I l may be varied considerably to afford displacementareas or pattern-s when pressure is applied to the printing platemounted thereon. As .shown, the projecting portions cover approximately25-40% of the surface area of the resilient material, but this area maybe varied within wide limits within the scope of the invention.

The printing plate H is of conventional form, and for convenience has onits printing surface a halftone indicated at I5, type It and bareportions ll. As shown in Figs. 1 and 2 a piece of sheet material I9, forexample, paper .004 inch in thickness, underlies the entire printingsurface. This releases pressure from non-printing areas. An additionpiece of sheet material It, such as paper preferably about .006 inch inthickness, underlies the halftone area for additional pressure. The baseportions indicated at H on the printing surface are not backed up withsheet material. Thus the portions 15 and It of the plate, whereincreased impression is desired, are relatively more firmly backed thanare the remaining portions of the plate. When a printing impression ismade, the more firmly backed portions of the plate provide increasedprinting pressure on the corresponding areas of the printing surface.

The printing block comprising the wooden mount 8, resilient underlay 9,sheeted backing and plate H, may be assembled and retained in assembledrelationship in any satisfactory manner, for example, by cement, or thecomponents may be held together by nails or screws 20. The retainingagent 20 should provide for limited vertical movement of the plate llupon the resilient backing 9, the plate should not be secured to theblock in such constricted fashion that the resiliency of the underlay islost. As shown in Fig. 2, a bore 2| may be provided in the printingplate which is slightly greater than the diameter of the nail extendingthrough the plate, the strip of sheet material, the resilient underlayinto the wooden base. Thus limited vertical movement of the plate uponthe resilient blanket is provided for.

It will thus be understood that a resilient printing element isprovided, adapted to absorb any inequalities in pressure derived from aninaccurate bed or inaccuracies in the wooden base. In connection withthe improved printing element, an impression cylinder having a hard,cylindrical periphery without overlay or packing may be employed. Theinvention includes the employment of a slightly yielding support for thematerial to be printed. Thus in flat bed presses an impression cylinderhaving a surface adapted to yield from .001 to .003 inchhas been foundto be very satisfactory. A hard rubber cylinder may be employed or, asshown in Fig. 8, a cylinder 5 having a cylindrical layer 6 of cork and asurface shell i of Formica, aphenol-formaldehyde condensation product,provides a surface adapted to absorb any slight inaccuracies in theprinting surface.

Other forms of resilient material may be employed within the scope ofthe invention, for

example, the rubber projections on the matting.

may be conical or irregular in shape, and the position of the matting 9may be reversed so as to have the projections l4 bearing against thewood mounting I0. In like fashion a resilient mat-ting having aplurality of adjacent cut-out portions providing a displ-aceable patternis within the scope of the invention.

The invention may also be utilized with various types of metal baseswell known to the art. In Figs. 3 and 4 the invention is illustrated inconnection with plates secured by hooks upon a metal base of thehoneycomb type. Obviously, the invention may also be employed upon metalbases (not shown) having grooves in which clamping devices are insertedto hold the plates in register upon the base. In Figs. 3 and 4 the metalbase 22 is shown provided with a plurality of cylindrical holes or bores23 diagonally arranged. A strip 2 of resilient material, similar to thatshown and described in connection. with Figs. 1 and 2, and comprising arubber matting 2'5 having fabric backing 2E and disc-like projections 21of compressible rubber, lies between the metal base .22 and the printingplate 28. For convenience, the printing plate is shown similar to thatillustrated; in Figs. 1 and 2 and has on its printing surface a halftone29, type 38 and low spots 3|. In a manner similar to that described inconnection with Figs. 1 and 2, the sections under the portions of theplate carrying the halftone 29 and type 30 may be built up by insertingpaper strips (not shown) OfitlliCkIlGSSGS of .006 inch and .004 inch,respectively, therebyincreasing the printing pressure upon the halftones and type. The sections under the low left bare.

It is preferred, however, to increase the pressure under the halftonesand type, by inserting metal plugs 32 in the bores 23 of the honeycombbase underlying the halftone'and type portions, as clearly shown inFigs. 3 and 4. The plugs 32 are. preferably provided with slots 32a andan adiacent yielding portion 32b to obtain a frictional engagement inthe bores 23. The top surface of the plugs may be flush with the surfaceof the base 22 thereby filling up the displacement space provided bybores 23 or the tops of the plugs may protrude slightly above the baseincreasing the pressure upon the printing surface above the plugs. Theplugs may also be provided with small bores 32c adaptedto be engaged bygripping members (not shown) to facilitate their removal. As clearlyshown in Fig. 3, when the plugs 32 are employed, the resilientprojecting members -21 are somewhat compressed before being subjected toprinting pressure and, obviously, cannot extend into the bores 23 aswhen the plugs are removed. The resilient matting 2A is preferablycemented to the bottom of plate 2123. Highly satisfactory results havebeen obtained by employing "plates carrying the resilient matting whichare .006 inch above normal type high, and accordingly, in utilining theinvention, the standard metal base of .759 inch thicknessis preferablyout down to .715 inch to compensate for the insertion of the rubbermatting of .046 inch in order that the improved printing assembly mayconform and be utiiized with standard beds. The invention may likewisebe practiced by utilizing bases of standard thickness by reducing thethickness of the plates. For example, the standard thickness ofelectrotypes for flat bed presses is .152 inch, and the metal on theback of the electrotype may be shaveddown until it is .112 inch thick.

In this manner a highly satisfactory metal printing base is provided,adapted to print evenly and to absorb any inaccuracies in the bed orbase. It will be understood that an impression cylinder spots 3! arepreferably having a smooth, peripheral surface may be employed withoutpacking or overlay. A cylinder having a slightly yielding surface asshown in Fig. 8 may be utilized.

The invention may likewise be utilized in rotary presses having animpression cylinder 38 and plate cylinder 39 rotatably carried on shafts40 and 4|, respectively, of the press. The impression cylinder 38 has asmooth, peripheral surface 42 and preferably does not carry any overlayor packing. The impression cylinder may have a slightly yielding surfaceadapted to absorb any inaccuracies in the surface of the curved plate 43and for this purpose may be equipped with a cylindrical cork shell 53and a smooth surface shell 54 of Formica. The curved printing plate 43illustrated has a printing surface similar to that of the plate shown inFigs. 1 and 2 comprising a half tone 44, type 45 and low spots 46 and issecured to the plate cylinder 39 by hooks or clamping devices well knownto the art. A resilient strip 41 comprising a rubber matting 48, fabricbacking 49 and rubber disc-like projections 50, is suitably secured tothe bottom of the plate 43, for example, by adhesives or cement. Thecurved plates 43 are preferably cast or cut down until they are .04 inchthinner than the standard plates of 0.187 inch thickness usuallyemployed in rotary presses. In manner similar to' that shown in Figs. 1and 2, paper strips of a thickness of .006 and .004, respectively, maybe secured to the fabric backing 49 of the matting, by adhesives, orthey may be suitably secured to the bottom of plate 43. It will also beunderstood that the resilient matting 41 may be reversed so that theprojections 50 gear against the surface of the plate cylinder 39 andthat various shapes of projecting portions 50 may be employed within thescope of the invention in order to obtain a yieldably supported printingsurface adapted to equalize any variations arising from irregularitiesin the surface of the impression cylinder, the surface of the platecylinder, and the printing plates 43.

Compressible material which is not permanently displaceable may besubstituted for rubber in the resilient matting. For example, the use ofany resilient spongy material is contemplated, such as may be made bymixing flour of lead, or of a selected alloy of lead, with tin and/orzinc and/ or antimony with a substantial quantity of latex so that themetallic flour is uniformly distributed throughout the latex. During thevulcanizing process the metallic flour is fused so that, after cooling,a sponge-like metallic skeleton frame is formed.

It will also be understood that other methods and means of varying theamount of pressure in localized areas, for example, under half tones,other than thin strips of sheet material or protruding plugs inhoneycomb bases, may be employed within the scope of the invention. Forexample, the thickness or degree of hardness of the rubber matting maybe increased in areas where it is desired to apply additional pressureor the displacement space may be increased or constricted to secure thedesired pressure.

It will be understood from the foregoing that the invention broadlycomprises the provision of a resilient support for printing elements ofthe character mentioned, and the invention is not restricted to theparticular character or mode of applying such a resilient support. Onthe contrary, the invention consists broadly in the provision of anyresilient material beneath a printing element during the printingoperation in order that the printing element may be yieldably supported,and preferably includes a relatively less yielding support for thematerial to be printed, to the end that the printing impression may beuniform throughout its entire area.

It is believed that the invention will be fully understood from theforegoing description, and it is obvious that numerous changes may bemade in the form, construction and arrangement of the variouscomponents, Without departing from the spirit or scope of the invention,the forms herein described being simply selected embodiments for thepurpose of illustrating the invention.

Having thus described my invention and illustrated its use, what I claimas new and desire to secure by Letters Patent is:

1. In a structure for relief or letterpress printing, a printing basehaving a plurality of adjacent cut-out portions along its upper surfaceto provide a displacement space, a member, having a printing pattern,mounted upon the upper surface of said base, said pattern havingportions requiring different printing pressures to form an evenimpression, resilient material interposed between said member and saidbase, and means for varying the area of said displacement space toconform with the printing pressure requirements of said printingpattern.

2. In a structure for relief or letterpress printing, a printing platesecured to a base, said printing plate having a letterpress printingsurface requiring different printing pressures to form an evenimpression, resilient material interposed between said printing plateand said base, and means in the base supporting said resilient materialpermitting variation in the area of support of said printing plate,whereby the variations in the printing pressure requirements of theprinting surface of said plate may be obtained.

3. The structure specified in claim 2 in which the members disposed insaid bores have portions extending slightly above the upper surface ofsaid base.

4. The method of relief or letterpress printing with a letterpressprinting plate having a printing surface requiring different printingpressures to form an even impression, which comprises mounting saidprinting plate upon resilient ma- .terial interposed between said plateand a base to which the plate is secured, and inserting means in thebase supporting the resilient material permitting variation in the areaof support of said printing plate, whereby the variations in theprinting pressure requirements of the printing surface of said plate maybe obtained.

5. In a structure for relief or letterpress printing, a printing elementcomprising a base having a plurality of vertical bores, a metallicprinting plate secured thereon in a manner to permit limited verticalmovement, a sheet of resilient material underlying said plate, saidplate having a letterpress printing surface, portions of which requiredifferent printing pressures to form an even printing impression, andmembers inserted in said bores beneath the plate portions requiringincreased pressure.

PHILIP A. FRAZIER.

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